1. Field of the Invention
The present invention relates generally to a multiple diaphragm pump system, and, more particularly, to a control mechanism for sequentially driving a plurality of diaphragm pumps in the system.
2. Description of Related Art
Diaphragm pumps are well known and typically include a pumping chamber containing a fluid to be pumped therein, which chamber also has a flexible wall or diaphragm that on contracting discharges the pumped fluid into and along a desired outlet conduit. Many dual-chamber diaphragm pumps also have a working chamber provided with a working fluid (e.g., air) that expands the working chamber and simultaneously reduces the pumping chamber due to the flexing of the diaphragm to effect pressurized discharging of the pumped fluid. Conventional one-way valves maintain desired direction of fluids during operation. Also, diaphragm pumps of this character typically require control apparatus for cyclically supplying working fluid to the pump and discharging the working fluid from the pumping chamber.
A known version of diaphragm pumping system has two dual-chamber diaphragm pumps with a control mechanism that charges the working chamber of one diaphragm pump while venting the other pump. Such systems undesirably exhibit an xe2x80x9cover-centerxe2x80x9d problem characterized by the tendency of the control mechanism to be in equilibrium at extremes of the mechanical cycle, i.e., when one chamber is charged and the other is vented. On this over-center phenomenon occurring, the control mechanism resists charging or venting and, on occasion, actual stalling can occur. Moreover, especially at low cyclical rates, these prior systems tend to exhibit surging as the system lurches from one condition to another which degrades pumping efficiency and negatively affects the ultimate use object of the system. In an attempt to overcome surging, pumps of this kind have been operated at higher than normal fluid pressures which increases the momentum of the control mechanism thereby avoiding over-center failures. However, such high pressure use cannot always be employed, and even if capable of being used presents its own problems common to hydraulic systems generally. Also, surging has been reduced somewhat by reducing the fluid flow rate which reduces forces in the system that counteract control mechanism momentum. All in all, improvement in control mechanisms for diaphragm pumps is a desideratum.
U.S. Pat. No. 4,385,869, Omata, discloses a reciprocation pump consisting of four individual diaphragms cyclically driven by mechanical drive shafts (7) to pump a fluid along a common pipe (3).
U.S. Pat. No. 5,334,003 issued to Gardner pertains to an air valving system in combination with a double diaphragm which uses a bore system to open and close tapped openings to control fluid movement.
The known prior art all appears to be subject to the xe2x80x9cover-centerxe2x80x9d problem, and, therefore, not fully satisfactory in operation under all use circumstances.
It is therefore a primary aim and object to provide an improved fluid control mechanism for driving a multiple diaphragm pump.
A further object is the provision as in the primary object of a diaphragm pump and fluid control mechanism that has substantially eliminated the over-center tendency to stalling and surging over a wide range of fluid pressures and speed of operation.
In accordance with the practice of the present invention, a control mechanism is provided including a distributor plate sealingly and rotatably mounted onto a porting plate which sequentially supplies a pressurized fluid in timed relation to three or more diaphragms of a diaphragm pump system for flexing each diaphragm to force a pumped fluid along a common discharge conduit.